Calling different DOS commands needs different SETLFS treatment

[Yazwh0]

https://github.com/X16Community/x16-docs/blob/master/X16%20Reference%20-%2013%20-%20Working%20with%20CMDR-DOS.md#command-channel

When talking about the command channel, $=C is mentioned, however is the secondary address is 15 when calling SETLFS, this will result in a 'Syntax Error' being returned.

Using a value of 0 makes it work. However this is the opposite for commands such as G-P where 15 is needed and 0 errors.

I dont know the reason behind this, but its worth mentioning in the documentation somewhere as I had to trap the call the kernel uses to figure out the right value to send.

Additionally when calling DOS("$=C") from the command line the kernel actually passes in 0x60. I don't know what the top nibble means here, but should that also be documentation?

[mooinglemur]

Anything beginning with $ is a (virtual) file, not a command channel command. On a C64, you would do LOAD "$",8 (which always uses channel/secondary address 0)

This extends to the other "file" type operations like filtered directory lists, and newly on the X16, the cwd listing.

[mooinglemur]

The X16 DOS command looks specifically for $ as the first character of its string argument, which routes it to channel 0. Any other character routes the string to channel 15.